The present invention relates to a variable geometry tracked vehicle designed so as to be able to move, optionally whilst transporting a load, on a path defined as being the natural path of man within an installation.
More specifically, the tracked vehicle according to the invention is more particularly designed in such a way as to be able to clear doors, move up or down staircases having several flights of stairs, take elevators and clear or get round minor obstacles.
This vehicle must also be able to transport operational modules appropriate for each mission to be fulfilled, whereby said missions can vary widely and in particular cover the inspection, dismantling or decontamination of a nuclear installation and fire fighting.
Existing tracked vehicles will now be described and discussed. For this purpose, said vehicles will be discussed as a function of the number of tracks, as well as the internal or external non-tracked bodies and caterpillared bodies thereof. A tracked body is being defined as a non-deformable solid, which directly participates in supporting one or more tracks, whereas a non-tracked body is defined as a non-deformable solid which does not support a track. A non-tracked bodyis said to be external if it constitutes an appendage and internal if it constitutes an intermediate connecting element between several tracked bodies.
On the basis of these definitions, the simplest known vehicles are those having two tracks integral with a single tracked body. Conventional military assault tanks and certain civil, military or nuclear tanks fall into this category. In their basic concept, these vehicles are particularly unstable, because they have no active means for controlling the posture or attitude, i.e. the shape or form of the vehicle, the position of its centre of gravity with respect to support points and the orientation of the inertia with respect to said support points.
As is more particularly illustrated by French Pat. No. 2 450 191, the stability of vehicles of this type can be improved by articulating on the tracked body a non-tracked body supporting the useful load. In this case, it is possible by moving the centre of gravity of the vehicle by pivoting the useful load, to improve the stability thereof when it is moving along a slope.
Certain of the vehicles belonging to this first category are able to take staircases. However, their performances are limited by the fact that, by their very nature, they have no intrinsic posture or attitude control, i.e. the attitude cannot be controlled if the vehicle has no external non-tracked body. Thus, there is a risk of turning over when clearing a marked obstacle, such as the nosing of a stair, as a result of lack of control of the centre of gravity position. Moreover, the vehicle can drop suddenly after clearing a peculiar point, particularly when arriving on the landing of a staircase. Moreover, on increasing the vehicle length, so that it can remain stable on the nosings of stairs, said increase in the overall dimensions of the vehicle is prejudicial when it arrives on landings, which makes it necessary to perform a half or quarter turn on the spot in a space which can be extremely limited.
A second type of tracked vehicle is illustrated by French Pat. No. 2 523 914. This is a vehicle having two variable configuration tracked and five caterpillar bodies constituted by a central body and two systems of articulated rods having two segments. This vehicle is in fact a variant of the first type of vehicle referred to hereinbefore, where an intrinsic attitude control is possible in the frontal plane.
Apart from its complex construction, this vehicle suffers from the disadvantage that it is difficult to obtain the large overlength on the ground necessary for the stability of the vehicle on a staircase. Moreover, the lateral guidance of the tracks is difficult to bring about and it is possible for the latter to be removed. Finally, the deformation of the tracks prevents any intermediate guidance between the pulleys, so that it is possible for the tracks to sink into an obstacle when their rigidity is not sufficient.
A third known tracked vehicle type has four caterpillars, each mounted independently on a track body, the four tracked bodies being articulated on an internal non-tracked central body. Such a vehicle is more particularly illustrated by Japanese patent application No. 83-804 872/44. The independent articulation of each of the tracked bodies on the central non-tracked body gives this vehicle particularly interesting possibilities for the intrinsic control of the attitude.
Although said means is very ingenious, it suffers from the disadvantage that the non-tracked central body can rub or even jam on a pointed object when clearing the same. Moreover, there is an interlink between the functions of varying the configuration (making it possible to adapt to the ground) and the intrinsic control of the attitude (making it possible to control the centre of gravity position). Therefore, when the vehicle moves on a slope, it is not possible to simultaneously ensure an optimum configuration of the tracked bodies and a modification of the attitude of the load e.g. making it possible to keep same horizontal.
Another vehicle is known, which has four tracked mounted in pairs on two tracked bodies articulated about a common axis. The "Spider" vehicle of the British organisation AERE Harwell belongs to this category. Compared with the previously mentioned vehicle having an intermediate non-tracked body, said vehicle makes it possible to eliminate the problem of clearing a pointed obstacle. However, this vehicle still suffers from the disadvantage of having few intrinsic attitude control possibilities, the two front tracks only constituting a clearing aid not making any significant modification possible to the centre of gravity of the complete vehicle. Moreover, said vehicle is not reversible, i.e. it is necessary for it to make a half turn in order that it can take any obstacle located to the rear.
Another known tracked vehicle has six caterpillars mounted in pairs on three tracks bodies directly articulated to one another. This vehicle, called the "Marauder" manufactured by the British company Morfax, corresponds to the preceding vehicle in which a supplementary tracked train has been added at the rear to make the vehicle symmetrical. Although this eliminates the disadvantage of non-reversibility of the previously mentioned vehicle, the possibilities of intrinsically controlling the attitude remain limited and the presence of three tracked trains makes this vehicle relatively complex.